A ir. CLARK : THE CRmOrDS OF THE INDIAN OCEAN. 47 



j^ P, usually small and weak, much shorter than the succeed- 

 ing pinnules, rarely similar to, and as large as, or slightly 

 larger than P,. 



k' one or more of the proximal pinnules enlarged, stifl'ened, 

 and spine-like, usually with less than 18 segments ; 

 division series well separated, the component ossicles 

 with prominent ventrolateral processes. 



(O) STEPHANOMETRID.^, p. 131. 



(67. keys 5, 11.) 



k'^ proximal pinnules all tiagellate, at least distally, with 

 more than 20 segments ; division series usually in close 

 apposition laterally, without lateral processes. 



(0) MARIAMETIRD^, p. 139. 



[Of. keys 5, 13.) 



3. — Key to the Familie.'^ of the CoMATrrLiD.s including Species with five 



Arms only. 



a' Arms short ; a pseudo-syzygy between the first two post-radial ossicles (the 



equivalents of the elements of the IBr series) and a syzygy between the fifth 



and sixth; proximal pinnules stout and triangular, with short segments, the 



first always on the second and the second always on the fourth post-radial 



ossicle; third post-radial ossicle always without a pinnule; disk small and 



compact, never black. 



(0) zygometrid^, p. 99. 



(Cf. key 9.) 



a'' arms very long and exceedingly slender ; never a pseudo-syzygy between the 

 first two post-radial ossicles (IBr series absent) ; proximal pinnules exceedingly 

 slender, with much elongated segments ; first pinnule usually on the fourth 

 post-radial ossicle; but if it occurs on the second, then tjie second is on the 

 third ; disk large, extending far up on the arms, black in colour. 



(M) PENTAMETROCRINIDiE, p. 247. 



{Cf. key 21.) 



4. — Keys to the Families of the Comatulids including Species with ten 



Arms. 



a' Ten radials, each bearing an undivided arm. 



(M) pentametrocrinid.^, p. 247. 

 (Cf. key 21.) 



a* five radials, each bearing a post-radial series which divides once. 



b' a circlet of basals separates the centrodorsal from the radials ; centrodorsal 



